[javascript] How to copy static files to build directory with Webpack?

You don't need to copy things around, webpack works different than gulp. Webpack is a module bundler and everything you reference in your files will be included. You just need to specify a loader for that.

So if you write:

var myImage = require("./static/myImage.jpg");

Webpack will first try to parse the referenced file as JavaScript (because that's the default). Of course, that will fail. That's why you need to specify a loader for that file type. The file- or url-loader for instance take the referenced file, put it into webpack's output folder (which should be build in your case) and return the hashed url for that file.

var myImage = require("./static/myImage.jpg");
console.log(myImage); // '/build/12as7f9asfasgasg.jpg'

Usually loaders are applied via the webpack config:

// webpack.config.js

module.exports = {
    ...
    module: {
        loaders: [
            { test: /\.(jpe?g|gif|png|svg|woff|ttf|wav|mp3)$/, loader: "file" }
        ]
    }
};

Of course you need to install the file-loader first to make this work.